There are numerous surgical, cosmetic, therapeutic and dermatological procedures that involve precise placement of medical instruments on a body surface and/or the need to repeat a procedure multiple times at various locations on a body surface. Hair transplantation surgery is one example of such procedures, and it typically involves harvesting donor hair grafts from “donor areas,” and implanting them in one or more bald areas (“recipient areas”). Hair transplantation surgery is a very labor-intensive and complex procedure that requires great skill and precision. When performed completely manually, hair transplantation surgery typically requires multiple, lengthy surgical procedures performed over time. As such, the assignee of the present application has developed an image-guided system for harvesting follicular units from a body surface, as described for example in U.S. Patent Publication Number 2007/0106306, which is hereby incorporated by reference. Image guidance is often used to direct movement of automated systems, such as a system for harvesting and implanting follicular units and/or performing other procedures on the skin or other body surfaces. One example of an image-guided, automated method and system is described in U.S. Patent Publication Number 2012/0158019, which is hereby incorporated by reference.
In performing a procedure on a body surface of a patient, it is often necessary or desirable to perform the procedure on multiple portions of the body surface, with each subsequent portion located immediately adjacent to the prior portion so that there are no gaps between, or overlap of, the multiple body surface portions. In other procedures, it may be desirable to have specific and/or consistent amounts of gaps or overlaps between the multiple body surface portions. Also, using some automated systems, such as those described in reference to certain embodiments of the above-referenced patent applications, it may also be necessary to use fiducial markers to guide the system to perform the procedure. In any of these cases, it can be challenging performing a procedure on multiple body surface portions located in desired locations relative to one another. Typically, for example, this may involve manually moving measuring devices, manually marking skin surfaces, approximating locations where prior procedures were performed, and the like. It can also be challenging to assure proper, stable and consistent positioning of fiducial markers in a treatment area. Various embodiments described below seek to address at least some of these challenges.